I'm in the process of Cerakoting a few of my own guns. I have several friends that know me well and how CDO( it is not OCD, they need to be in the correct order) I can be about my work. They have ask me about doing things for them even though they have not seen anything I have done. I'm really have not been interested in doing it, but I have got a bit of money Spent between sprayers,hoses,filters,cabinets,Alox,etc. I'm beginning to consider doing some but what to everything legit.
I know that gunsmiths are required to have an FFL and I would assume that Cerakoting would count as a Gunsmithing. I believe I could cerakote everything except the lower receiver of an AR without an FFL. Is that correct?
If I like how mine turns out I and I choose to start doing others, I will get an FFL. I already have an LLC that I could convert to use so that is covered.
What FFL is required to Gunsmith and how much would that end up costing me?

I'm on the fence about this and probably will not be worth the money. But just wondering

07 manufacturer.

A type 07 is for a manufacturer.  If you are doing gunsmithing, including cerakoting you only need a 01 license.

Get an 01 FFL and take in customer firearms for gunsmithing, which Cerakoting would be described as.

If you get an 07 FFL, you can coat guns of which do not belong to a customer that are for sale....but you'd have to pay over $2k (iirc) a year for insurance that you'll never need or use.

Correct.